It's simple, according Yoshida, the console wasn't shown because its design is not finished, but he also said that its hardware is not finished either.

http://n4g.com/news/1178865/ps4-hardware-design-not-finalized-sony

So, I think the final hardware will be even better that the current one(we only know about memory so far).

Not likely. It's supposed to launch this holiday.

They are still deciding how to get all the hardware into a tiny plastic box that won't melt down.

understandable. can't wait for E3

it cant get no better then what they showed us.

They will adjust it just enough to out do what MS next console will do.. to cut on cost. lol

They will wait to see what Ms does and change a few things maybe even ad things. Sony haven't been stupid this time around